How do I claim an unmanaged Facebook Page for my Instagram account?

If you've created a business account on Instagram, a Facebook Page may exist for your business even if someone from your business didn’t create it. For example, if you choose not to connect to a Facebook Page at the time you create a business account on Instagram, an unmanaged Facebook Page is automatically created so that people can find your business more easily and check into your business. You can request to claim the Page and become its admin.